[CJH366]

I have a small, single story ranch house with a dirt cellar underneath it that was dug out long after the house was built. I haven't measured it exactly yet, but it is afairly small area; approximately 8 ft wide, 10-12 ft long and 7-8 ft deep with a small conxcrete stairwell. I already know that I am going to have to install permanent jackposts under the footers if I leave it as it is. With the escalation of severe weather that requires being underground in this area, I am considering putting in real walls and a floor rather than the posts. What is the best way to go about installing these in an existing dirt cellar dug out underneath a house? Which is more feasible to use for the walls, poured concrete or blocks? And how should the walls be reinforced with either of the two? Thank you.